Boat hull for planing craft



Oct. 29, 1963 7 MGNEIL TA 3,108,561

BOAT HULL FOR PLANING CRAFT INVENTORS A. McNEIL E cN El L EDWARD WIL IATTORNEY Fig.2

1963 E. A. MQNEI'L ETAL BOAT HULL FOR PLANING CRAFT 4 Sheets-Sheet 2Filed Dec. 22, 1961 io FORW Z 1963 E. A. MCNEIL ETAL BOAT HULL FORPLANING CRAFT 4 Sheets-Sheet 3 Filed Dec. 22, 1961 Fig.4

{NVENTORS A E ATTORNEY EDWARD WILLIAM Oct. 29, 1963 E. A. M NEIL ETAL3,103,561

BOAT HULL FOR PLANING CRAFT Filed Dec. 22, 1961 4 Sheets-Sheet 4 Fig.5 V

cNEl WILLBIYAM E- cNEl Z /fi W TTORNEY United States Patent 'Ofiice35-,lfi 85fil Patented Oct. 29, 1363 3,108,561 BQAT HULL F011 PLANHJGCRAFT Edward A. McNeil, 14 Park; St, and William E. McNeil,

both of Roseland, Ni; said Wiliiam E. McNeil assignor to said Edward A.McNeil Fiied Dec. 22, 1951, Ser. No. 161,544 9 Claims. Cl. 114-665) Thepresent invention relates to hulls for boats and the like, and, moreparticularly, to an improved variable displacement planing hull of theair supported type.

In propelling boats through water a very large percentage of power,which otherwise could be utilized to move the boat forwardly at agreater speed, is wasted by shoving the water aside at the bow toproduce a bow spray and at the sides to produce a wake. The side spraygenerated by a planing surface can have a force of considerablemagnitude. The more spectacular and impressive the side spray and wakeare, the greater is the waste of power. The magnitude of this wastedpower can be appreciated by noting the violent tossing of sizable boatsat anchor when comparatively smaller power boats pass by. A conservativeestimate is that at least 40% of the propulsion power of the boat is sowasted.

While the wasting of available power by wetted surface friction betweenthe boat hull and the water and by suction drag under the stern of theboat hull has been recognized and has led to the design of better hulls,such designs are not entirely satisfactory with respect to the problemwhich they purport to solve and serve no useful purpose in minimizingbow spray, side spray and wake to prevent the resulting waste of power.

Accordingly, an object of the present invention is to provide animproved hull for planing craft which greatly minimizes the waste ofpower caused by generating a how spray, side spray and a wake and whichat the same time greatly reduces wetted surface friction and sternsuction.

Another object is to provide such a hull which planes in substantiallythe same attitude it is in when resting on the water.

Another object is to provide such a hull which has excellent lateralstability.

Another object is to provide such a hull which has excellentlongitudinal stability.

Another object is to provide such a hull which is more comfortable tothe passengers as the bow spray and side spray which otherwise would bedriven into the boat by wind is eliminated.

Another object is to provide such a hull which by reason of its minimumspray and wake is more difiicult to detect firom land, sea or air andtherefore has strategic value for use with military craft.

Another object is to provide such a hull which more fully utilizes apower plant of a given size to propel the boat at a greater speed or toenable the boat to carry a greater load at the same speed.

Another object is to provide such a hull which enables a boat of a givensize to be driven more economically by a smaller power plant.

Another object is to provide such a hull which assuges its passengers asofter cushioned and less bumpy n e.

Another object is to provide such a hull which by reason of a wide areaof positive lifting pressure on its bottom surfaces is less affected bylocal disturbing water [forces to induce pitching or porpoising.

Another object is to provide such a hull wherein its trim is lessaffected by the shifting of internal weigh-ts, passenger loaddistribution or fuel consumption by reason of the wide area of positivelifting pressure on its bottom suriaces.

Another object is to provide such a hull whose visible form and contoursdo not clash with the publics concept of acceptable lines, and which asa result of a deep wide chine line has more useable internal space.

Another object is to provide such a hull whose curved bottom surfacesare self supporting and possess great structural strength, withoutcomplex internal bracing.

Another object is to provide such a hull which by reason of its positivelift in the stern area is better able to support heavy outboard motorsor inboard-out drives which are normally located at or near the stern.

Another object is to provide such a hull wherein the stern does notsquat down to invite swamping by a following sea.

Another object is to provide such a hull which is adapted for use withseapl-anes or amphibious craft of civilian or military types.

A further object is to provide a hull structure which can be embodied innewly fabricated bulls and can be applied to existing hulls to improvethe functioning thereof.

A still further object is to accomplish the foregoing in a simple,practical and economical manner.

. Other and further objects of the invention will be obvious upon anunderstanding of the illustrative embodiment about to be described, orwill be indicated in the appended claims, and various advantages notreferred to herein will occur to one skilled in the art upon employmentof the invention in practice.

In accordance with the present invention, it has been discovered thatthe foregoing objects can be accomplished by providing a planing hullwhich comprises a how, a stern, sides and a bottom, the bottom havingchines at the sides thereof, a keel, and a generally concave downwardlyfacing tunnel on the underside of the bottom between the keel and eachof the [chines which elements appear to have critical relationships byreason of these arrangements and dimensions.

A preferred embodiment of the invention has been chosen for purposes ofillustration and description, and is shown in the accompanying drawings,forming a part of the specification, wherein:

FIG. 1 is a side elevational view of a hull in accordance with thepresent invention.

FIG. 2 is a bottom plan view of the hull.

FIG. 3 is an outline view of a family of curves illus trating half widthtransverse sections taken through points of the forward or bow zone andthe forward portion of the body zone of the hull, and at the stern ofthe hull.

FIG. 4 is a view similar to FIG. 3 taken through lengthwise spacedpoints of the body zone of the hull.

FIG. 5 is an outline view of a transverse half width section takenthrough the body zone of the hull and having dimensional legend thereonfrom which the data in Table I set forth hereinafter is compiled.

FIG. 6 is an outline view of a transverse half width sectionillustrating a modified hull.

Referring now to FIGS. 1 and 2 of the drawings in detail, a boat hull isshown which generally comprises a bow 25, a stem or transom :26, sides27, a bottom 28 having a keel 29 at the centerline thereof, and chines30 defined by the junction of the sides and the bottoms.

The hull is divided lengthwise into spaced transverse sections numberedfrom zero to twenty (bow to stern) to indicate the distance in feetbetween the bow and each transverse section.

The transverse sections from 0 (how) to about 5 shown in FIG. 3constitute the forward section of the hull which is generally V-shapedfrom the how 25 to about section 4. The transverse sections from about 6to 20 (stern) shown in FIGS. 3 and 4 constitute the body zone of thehull. The lower edge of the keel 29 is disposed in a substantiallyhorizontal plane from about section to the stern. This plane is calledthe keel plane and is the plane from which vertical or height dimensionsare taken.

The transverse sections are indicated by broken lines in FIGS. 1 and 2and are shown in half width outlines in FIGS. 3 and 4 with likereference numerals applied to like sections.

In the forward zone, the sides and bottom diverge aftwise from the bow.The bottom also diverges upwardly and outwardly from each side of thekeel and has a concave curvature which becomes more pronounced from justaftwise of the bow towards the body zone (FIG. 3). The sides meet thebottom at an included angle which decreases in magnitude aftwise fromabout section 3 to about section 8, whereby the chine-like structurebecome more pronounced and the sides more closely approach the verticalin the aftwise direction.

At about the transverse section 6 where the body zone commences, thecurvature of the bottom 28 and the height of the chines 30 above thekeel plane is such that the maximum height of the bottom portion abovethe keel plane slightly exceeds the height of the chines to form atunnel-like formation in the bottom of the hull at each side of the keel29 which formations are referred to hereinafter as tunnels 31. Thedimension by which the tunnel height exceeds the chine height increasessharply from ections 6 to 8 while the tunnels become somewhat wider(FIGS. 2 and 3).

The tunnels 31 continue to extend aftwise from section 8 to the sternand the height thereof decreases on a slope of about 3 to 4 to the keelplane (FIG. 1). The dimension by which the tunnel height exceeds thechine height now decreases aftwise; and the width of the tunnels (theis, the horizontal distance between keel and the chines) decreasesslightly (at a rate of about 10%) in an aftwise direction. Thus, betweenthe section 8 and the stern, the cross-sectional area of the tunnels,which is defined by the curvature of the bottom and a straight line fromthe keel to the chines (FIG. 4) decreases aftwise, for example, the areaat section 8 is about three to four times as great as this area at aboutthe stern.

Preferably, the hull is provided with more or less conventionalanti-trip chines 32 extending from about the transverse section 12 tothe stern (FIGS. 1 and 4). The presence of these anti-trip chines isdisregarded in measuring the chine angles (Table I) at these transversesections. However, since the anti-trip chines are disposed at an angleof 45 to the horizontal, the chine angle is 45 less than the angle givenin Table I when the anti-trip chines are regarded in measuring the chineangles at sections 12 to 20.

When the hull is normally loaded, the keel plane slants forward and thehull is immersed so that the water line WL extends from about section 7or just aft thereof to the stern (FIGS. 1, 3 and 4). Thus, between aboutsections 6 and 7 the chines and the tunnels are above the water line,and between sections 8 and about 14 the middle of the tunnels is abovethe water line but the chines are immersed to provide a sealed tunnelarea, whereby air and turbulent water caused by bow spray beginning atabout section 3 are scooped from about sections 5 to 7, are fed into thesealed tunnel area commencing at about section 7, and are confined toflow aftwise through the tunnels and exit at the stern. Since the sealedtunnel area decreases aftwise, the air flowing therethrough iscompressed so that the entire body zone of the hull practically rides onair to greatly decrease friction drag on the hull.

The portions of the bottom of the hull providing the tunnels 31 have acurvature produced in a beam which is fixed at one end and is deflectedby applying a com- 4 pression force at its other end in a directiontowards the fixed end, which curvature is generally elliptical. Suchtransverse formations have good structural strength.

In FIG. 5, an outline of a half-width transverse section is shown whichincludes dimensional legend referenced for use in connection with thetable of dimensions about to follow, the significance of the legendbeing explained in the footnotes to the table. As indicated in thisview, the base of the keel has a width of one inch in the body zone ofthe hull.

In order to demonstrate the practical aspects of the present invention,a boat hull having a length of about twenty feet and a nominal beam ofabout seven feet and nine inches was constructed in accordance with thedimensions set forth in Table I.

Table I L, KA, CA, W, H, TW, TII, CH, feet degrees degrees inches inchesinches inches inches LDistance from bow KA-Kcel angle (included).CAChine angle.

WHall width between sides at top. H-Height of sides above keel plane.'IW-Tunnel width.

TIT-Tunnel height (maximum). CIT-Chine height above keel. WL-Water linebegins.

Certain of the dimensions in Table I, particularly the keel and chineangles, are only approximate because they were measured on theconstructed hull.

This hull was propelled by a 50 horsepower outboard engine driven atfull speed on Barnegat Bay, New Jersey, and attained a speed of about 35mph. without producing any perceptible bow spray or wake, and planedsubstantially horizontally, that is, in about the same relative positiveit is in when resting on the water with the chines at sections 8 to 20remaining fully immersed. The hull also had excellent lateral stability,particularly on sharp turns, and had excellent maneuverability.

Furthermore, the hull did not pound in rough water as the deep chinesprovide additional variable displacement cushioning and provided a dryride for its passengers. The hull did not ride how high to obstructvisibility nor did the stern squat down to invite swamping.

It is believed that the foregoing performance is due to the constructionand arrangement of the keel, chines and tunnels whereby turbulent waiterand air is scooped and deflected into the tunnels and a minimum of wateris permitted to escape to produce a bow spray which wastes power. Theair is entrapped in the tunnels and is compressed multi-stagewise bysuccessive waves and surface foaming as it flows towards the stern toprovide a cushion of air for lifting the hull and on which the hullrides to reduce surface friction between its bottom and the water and toalso eliminate suction drag under the stern.

Furthermore, it should be noted that the chine angles CA are sharpest atabout section 7 where they first enter the water and gradually decreaseas they approach the stern FIGS. 3 and 5, Table I). These angles therebyprovide a knifelike entrance to allow forward motion of the hull with aminimum of disturbance of the water, and provide a very gradual changeof displacement in rough Water with a resulting snubbing action as thewater is displaced transversely towards the center of the tunnels whichmakes for an exceptionally smooth ride. Also, the sharpness of theangles where the chines first enter the water provides excellenttracking and unusual lateral stability which aids in holding a straighttrue course in wind and rough water. Such deep forward tracking providesremarkable stability on tight fast turns and provides in efiect a pivotpoint about which the powered stern can be steered.

Still further, it is believed that one of the most important featurescontributing to overall efliciency of the hull is that the gradual anduniform flattening of these angles maintains a constant, continual anduniform change in flow direction of the adjacent water particles fromwhich the dynamic hull lift is obtained. Thus, by imparting a constantchange of direction it is possible to effectively spread the lift overthe entire bottom area in the body zone, and, by controlling air andwater flow in the foregoing manner, a positive pressure can be producedat the stern area where heretofore a considerable suction drag has beenexperienced with conventional hulls. As a result, the hull will notappreciably pitch or roll due to disturbing forces such as rough water,wind and load shift. 7

The twin tunnels assure an ample supply of undisturbed water in which asingle propeller can operate to drive the hull at a high speed, wherebytwin propellers are not required as in the case of catamarans or twinhulls. The hull in amordance with the present invention is ideal forconventional outboard motors, turbo jet drives and for inboard-out'drivepower plants where the drive shaft extends through the transom.

in FIG. 6, a modified form of hull is shown wherein the tunnels 31 aresubdivided into a number of substantially parallel lengthwise extendingflutes 33 having a concave contour to provide a group of small tunnelswithin the tunnels 31 which are separated by small keel-like portions orsteps 34 adapted to further improve the stability of the hullparticularly in extremely rough seas. These small tunnels and steps aredimensioned to follow the general outline of the hull structure shown inFIGS. 3 and 4. Preferably, these tunnel-like sections 33 have a widthabout four to about six times greater than their depth.

While the present invention has been described in connection with newlyfabricated hulls, it will be understood that it can be applied to hullsalready in use. For example, a hull having a V or rounded contouradaiacent its keel may be modified by attaching a supplementary form tothe underside which provides a deep chine and a half tunnel sectionlaterally outward of the contours along the keel, whereby the hull ismodified to embody the chine and tunnel structure described herein.

From the foregoing description, it will be seen that the presentinvention provides a simple, practical and efficient hull design for thepurposes indicated herein.

As various changes may be made in the form, construction and arrangementof the parts herein, without departing from the spirit and scope of theinvention and without sacrificing any of its advantages, it is to beunderstood that all matter herein is to be interpreted as illustrativeand not in any limiting sense.

We claim:

1. A hull comprising a how, a stern, sides, a bottom having a keel atthe center line thereof, and chines defined by the junction of saidsides and said bottom, said hull having a forward zone wherein saidsides and said bottom diverge aftwise and diverge upwardly and outwardlyfrom said keel, said 'hull having a body Zone extending aftwise from saiforward zone to said stern wherein said bottom has an identical tunnelof generally elliptical curvature between said keel and the chine ateach side of the hull, the length of said body zone being about threetimes greater than the length of said forward zone and thecross-sectional area of said tunnels at a forward section of said bodyzone being about three times greater than at the stern end of saidtunnels and said hull having a beam about equal in width to the lengthof said forward zone, the foremost transverse sections of said body zonehaving the tunnels and chines positioned above the water line of thehull to provide scoops and the immediately aftwise following sections ofsaid body zone having the chines positioned to extend below the waterline of the hull and having at least a substantial portion of thetunnels above the water line of the hull for receiving air and turbulentWater from the scoops, said tunnels decreasing in height and width fromthe scoops to said stern to entnap and confine air and water betweensaid keel and said chines and to allow the air and water to exit at saidstern end of said tunnels.

2. A hull according to claim 1, where said keel extends furtherdownwardly than said chines throughout its entire lengthwise extent andis disposed in a substantially horizontal plane from about the stern toabout the middle of said forward zone, the maximum height of saidtunnels at any given transverse section being nearer said chines thansaid keel.

3. A hull according to claim 1, wherein said tunnels at about theforemost section of said body zone have a horizontal width about twotimes greater than the vertical height thereof and said tunnels atimmediately aftwise sections in said body zone have a horizontal widthabout three times greater than the vertical height thereof.

4. A hull according to claim 3, wherein said tunnels at the sternportion of said body zone have a horizontal width at least about sixtimes greater than the vertical height thereof.

5. A hull according to claim 2, wherein the height of said chines abovethe said keel in said body zone decreases in an aftwise direction.

6. A hull according to claim 5, wherein the vertical height of saidtunnels slightly exceeds the height of said chines above said keel atthe stern, and the vertical height of said tunnels exceeds the verticalhigh of said chines in a forward section of said body zone by adimension about five times greater than at said stern.

7. A hull according to claim 6, wherein the vertical height of saidtunnels slightly exceeds the height of said chines in the foremostsection of said body zone.

8. A hull according to claim 1, wherein said tunnels are subdividedcrosswise into lengthwise extending small tunnel-like sections.

9. A hull according to claim 8, wherein said tunnel-like sections aregenerally concave and a step is provided between adjacent tunnel-likesections.

References @ited in the file of this patent UNITED STATES PATENTS1,176,446 Hayman Mar. 21, 1916 1,726,439 Korvin-Kroukovsky Aug. 27, 19291,767,815 Rohrbach June 24, 1930 2,020,792 Maynard et al Nov. 12, 19352,185,430 Burgess Jan. 2, 1940 2,938,490 Martin May 31, 1960 2,965,061Bank et al Dec. 20, 1960

1. A HULL COMPRISING A BOW, STERN, SIDES, A BOTTOM HAVING A KEEL AT THECENTER LINE THEREOF, AND CHINES DEFINED BY THE JUNCTION OF SAID SIDESAND SAID BOTTOM, SAID HULL HAVING A FORWARD ZONE WHEREIN SAID SIDES ANDSAID BOTTOM DIVERGE AFTWISE AND DIVERGE UPWARDLY AND OUTWARDLY FROM SAIDKEEL, SAID HULL HAVING A BODY ZONE EXTENDING AFTWISE FROM SAID FORWARDZONE TO SAID STERN WHEREIN SAID BOTTOM HAS AN INDENTICAL TUNNEL OFGENERALLY ELLIPTICAL CURVATURE BETWEEN SAID KEEL AND THE CHINE AT EACHSIDE OF THE HULL, THE LENGTH OF SAID BODY ZONE BEING ABOUT THREE TIMESGREATER THAN THE LENGTH OF SAID FORWARD ZONE AND THE CROSS-SECTIONALAREA OF SAID TUNNELS AT A FORWARD SECTION OF SAID BODY ZONE BEING ABOUTTHREE TIMES GREATER THAN AT THE STERN END OF SAID TUNNELS AND SAID HULLHAVING A BEAM ABOUT EQUAL IN WIDTH TO THE LENGTH OF SAID FORWARD ZONE,THE FOREMOST TRANSVERSE SECTIONS OF SAID BODY ZONE HAVING THE TUNNELSAND CHINES POSITIONED ABOVE THE WATER LINE OF THE HULL TO PROVIDE SCOOPSAND THE IMMEDIATELY AFTWISE FOLLOWING SECTIONS OF SAID BODY ZONE HAVINGTHE CHINES POSITIONED TO EXTEND BELOW THE WATER LINE OF THE HULL ANDHAVING AT LEAST A SUBSTANTIAL PORTION OF THE TUNNELS ABOVE THE WATERLINE OF THE HULL FOR RECEIVING AIR AND TURBULENT WATER FROM THE SCOOPS,SAID TUNNELS DECREASING IN HEIGHT AND WIDTH FROM THE SCOOPS TO SAIDSTERN TO ENTRAP AND CONFINE AIR AND WATER BETWEEN SAID KEEL AND SAIDCHINES AND TO ALLOW THE AIR AND WATER TO EXIT AT SAID STERN END OF SAIDTUNNELS.